The present invention concerns a gas turbine arrangement, comprising a compressor, with a rotor, a turbine, with a rotor and connected with the compressor, and a balancing member connected with the turbine rotor and arranged to counteract axial forces generated by the compressor rotor and the turbine rotor, wherein the balancing member is arranged to be activated by means of a pressure fluid.
In such gas turbine arrangements according to the prior art, the compressor rotor is usually coaxial with and connected to the turbine rotor. The compressor rotor and the turbine rotor are thereby usually carried in bearings which are arranged in the area of the opposite ends of the two rotors.
Since the compressor rotor and the turbine rotor usually have different kinds of blades, and, furthermore, since a higher power is usually produced by the turbine rotor, the axial forces which are generated by the two rotors and which are directed in opposite directions will not completely cancel each other. Consequently, a resulting axial force exists. In order to reduce the load on the axial bearing or bearings which will carry said resulting axial force, gas turbine arrangements according to the prior art are therefore provided with a balancing piston which is coaxial with the rotors and attached to that end of the turbine rotor which is turned away from the compressor rotor. The balance piston may thereby be formed by a disk-shaped piece which is integrated with an axle which via this piece is connected with and projects from the turbine rotor. In order to generate an axial force in the balancing piston, a part of the compressor air which is drawn off from the compressor for cooling purposes is conducted to the balancing piston and is allowed to exercise a force on the side of the balancing piston which is turned away from the turbine rotor. It is thereby even possible to exclude an axial bearing in this end of the compressor rotor/turbine rotor unit.
The compressor air which is used for the activation of the balancing piston is allowed to an as low extent as possible to flow out in the main flow channel of the turbine after having served its purpose. Any further utilisation of the compressor air does not take place.
A purpose with the present invention is to achieve a gas turbine arrangement which is arranged such that the pressure fluid which is used for activating a balancing member is used in such a way that a reduction of the total amount of compressor air which is drained off for, inter alia, cooling purposes in the gas turbine arrangement is possible or that a higher influence of the temperature of components included in the turbine is possible by means of a given amount of drained off compressor air. With xe2x80x9cinfluence of temperaturexe2x80x9d is here meant primarily cooling, but also heating of certain components during certain phases of operation may be desired and may take place.
This purpose is achieved with a gas turbine arrangement as initially defined, which is charaterized in that it comprises at least one channel which is arranged to lead at least a part of the pressure fluid used for said activation to at least a part of the turbine for influencing the temperature of the same. With influencing the temperature primarily cooling is meant, but it is of course also possible to use the pressure fluid for heating said part of the turbine if this is found to be advantageous.
According to a preferred embodiment, said part of the turbine is a rotor portion. Thereby the possibility is achieved, that by means of the pressure fluid cooling of the rotor portion is accomplished, which is desirable.
According to a preferred embodiment, the rotor portion is a rotor disk. Usually a cooling of the rotor disks of the turbine is desirable or necessary. Specific constructional solutions are however necessary in order to conduct cooling air to all of these. The use of the pressure fluid of the balancing member, which pressure fluid preferably comprises drained off compressor air, for influencing the temperature of one or more of the rotor disks of the turbine permits technically simple solutions for the conduction of the pressure fluid to the rotor disks, in particular since the balancing member suitably is arranged in association with the rotor disks.
According to a further preferred embodiment, the balancing member is attached to an end of the turbine rotor and said channel leads to a space formed between the end of the rotor and the balancing member. Thereby an appropriate cooling of the last one in a row of rotor disks is achieved.
According to a further preferred embodiment, the gas turbine arrangement comprises at least one leakage passage, arranged to allow leakage of the pressure fluid which has been used for said influence of temperature into a main flow channel in the turbine. Thereby a continuous flow of the pressure fluid into and through the space mentioned before is achieved. Furthermore, an advantageous cooling of that surface of the balancing member which together with said rotor disk define said space between the two is achieved.
According to a further preferred embodiment, the balancing member comprises an axle, which is coaxial with the turbine rotor and attached to the turbine rotor at the downstream end of the same. In a known manner the axle may comprise a disk-shaped piece, via which it is attached to the turbine rotor and which may define a wall against which the pressure fluid exercises its pressure in the direction towards the turbine rotor.
According to a further preferred embodiment, the previously mentioned channel extends through the axle from the outer circumference of the same and axially in the axle to said space. Preferably, the channel comprises at least one radial hole which extends from the outer circumference of the axle to the area of the centre of the axle and at least one axial hole which is connected with said radial hole and ends at said space. The pressure fluid may thus easily be conducted from the outside of the axle and into the closed space in which it may act as a cooling medium.
According to a further preferred embodiment, the balancing member comprises a pressure chamber, which comprises an opening for leading the pressure fluid into the same. Said channel is preferably connected to the pressure chamber. In such a manner, a reliable flow of the pressure fluid/pressure medium to the most downstream positioned rotor disk of the turbine rotor may be achieved.
Further advantages and features of the gas turbine arrangement according to the invention will be clear from the remaining dependent claims and from the following description.